1. Field of the Invention
The present invention relates to a method for producing a piezoelectric actuator which is used in apparatuses such as a liquid transporting apparatus.
2. Description of the Related Art
In a liquid transporting apparatus, a piezoelectric actuator which applies pressure for transporting a liquid is used. For example, in an ink-jet recording head described in Japanese Patent Application Laid-open No. 2005-168172, for manufacturing a piezoelectric actuator, firstly, a first insulating film (substrate) is formed on an upper surface of a channel forming substrate in which ink channels are formed, and a second insulating film (diffusion preventing layer) is formed by a sputtering method on an upper surface of the first insulating film. Further, a film for forming lower electrode which becomes a lower electrode is formed by the sputtering method on an upper surface of the second insulating film, and a piezoelectric precursor film which becomes a piezoelectric film (piezoelectric layer) is formed by a sol-gel method on the upper surface of the film forming lower electrode. Thereafter, for achieving piezoelectric characteristics, a stacked body including the piezoelectric precursor film is baked to crystallize the piezoelectric film thereby forming the piezoelectric film.
However, when an ink-jet recording head is manufactured by a method described in Japanese Patent Application Laid-open No. 2005-168172, a residual stress is generated in the second insulating film after the second insulating film has been formed. Therefore, when a piezoelectric precursor film is baked, the residual stress of the second insulating film is relieved, and an internal stress of the second insulating film is changed. Moreover, the second insulating film is deformed due to the change in the internal stress. At this time, a lower electrode and a piezoelectric film cannot follow the deformation of the second insulating film, and there is a possibility that the lower electrode is exfoliated from the second insulating layer, and a crack is developed in the piezoelectric film.